1. Technical Field
The present invention relates to a technology of synthesizing voices with various characteristics.
2. Related Art
Conventionally, there have been proposed technologies to apply various effects to voices. For example, Japanese Non-examined Patent Publication No. 10-78776 (paragraph 0013 and FIG. 1) discloses the technology that converts the pitch of a voice as material (hereafter referred to as a “source voice”) to generate a concord sound (voices constituting a chord with the source voice) and adds the concord sound to the source voice for output. Even though one utterer vocalizes the source voice, the technology according to this configuration can output voices audible as if multiple persons sang individual melodies in chorus. When the source voice represents a musical instrument's sound, the technology generates voices audible as if multiple musical instruments were played in concert.
Types of chorus and ensemble include: a general chorus in which multiple performers sing or play individual melodies; and a unison in which multiple performers sing or play the same melody. The technology described in Japanese Non-examined Patent Publication No. 10-78776 generates a concord sound by converting the source voice pitch. Accordingly, the technology can generate a voice simulating individual melodies sung or played by multiple performers, but cannot provide the source voice with a unison effect of the common melody sung or played by multiple performers. The technology described in Japanese Non-examined Patent Publication No. 10-78776 can also output the source voice together with a voice only having the acoustic characteristic (voice quality) converted without changing the source voice pitch, for example. In this manner, somehow or other, it is possible to provide an effect of the common melody sung or played by multiple performers. In this case, however, it is required to provide a scheme to convert source voice characteristics for each of voices constituting the unison. Consequently, an attempt to provide a unison composed of many performers enlarges the circuit scale for a configuration that converts source voice characteristics using hardware such as a DSP (Digital Signal Processor). In a configuration that uses software for this conversion, the processor is subject to excessive processing loads. The present invention has been made in consideration of the foregoing.